Biomimetic synthesis of sericin and silica hybrid colloidosomes for stimuli-responsive anti-cancer drug delivery systems

Colloidosomes are becoming popular due to their significant flexibility with respect to microcapsule
functionality. This study reports a facile approach for synthesizing silica colloidosomes by using sericin
microcapsule as the matrix in an environment-friendly method. The silica colloid arrangement on the
sericin microcapsules are orchestrated by altering the reaction parameters. Doxorubicin (DOX), used as
a hydrophilic anti-cancer drug model, is encapsulated into the colloidosomes in a mild aqueous solution
and becomes stimuli-responsive to different external environments, including pH values, protease, and
ionic strength are also observed. Colloidosomes with sub-monolayers, close-packed monolayers, and
close-packed multi-layered SiO2 colloid shells can be fabricated under the optimized reaction conditions.
A flexible DOX release from colloidosomes can be obtained via modulating the SiO2 colloid layer
arrangement and thickness. The close-packed and multi-layered SiO2 colloid shells can best protect the
colloidosomes and delay the rapid cargo release. MG-63 cells are killed when doxorubicin is released
from the microcapsules due to degradation in the microenvironment of cancer cells. The drug release
period is prolonged as SiO2 shell thickness and integrity increase. This work suggests that the hybrid
colloidosomes can be effective in a bioactive molecule delivery system.